Many sensors, such as for measuring oxygen in exhaust gases, use platinum as the electrode material because the platinum has high current density and good durability in high temperature environments where it is exposed to vehicle exhaust/gases. Some of these sensors are manufactured using electrolyte and ceramic materials that can be sintered at temperatures as low is 1300 degrees C. Sensors that are manufactured from laminated stacks of alumina, however, require sintering at higher temperatures, for example, around 1500 agrees C. When a platinum electrode material is sintered at 1500 degrees C., challenges develop that don't occur during sintering at 1300 degrees C. Primarily, the platinum electrode material tends to sinter and densify, which decreases its current carrying capacity and its porosity. If the platinum electrode sintered at 1500 degrees C. is used as an oxygen pump for an oxygen sensor, not as much oxygen can be transported through the platinum, lowering its efficiency.
One method for improving the efficiency of the platinum is to add ceramic powder to the platinum ink that is used to form the electrode. For example, if the ink is to be printed on a zirconia body, the ceramic powder is preferably zirconia. This technique has been found to increase the current density of the electrode sintered at 1500 degrees C., for example, from about 1 mA/cm .sup.2 to 5 to 7 mA/cm .sup.2 --when operated at 750 degrees C. But 5 mA/cm.sup.2 is still a very inefficient current density.